Motion-transmitting device.



No. 705,624. Paten ted July 29, 1902.

c. F. STOKES '81. c. E. McGLINCHEY.

MOTION TRANSMITTING DEVICE.

(Applichtion filed Nov. 9; 1899 j 2 Sheets-Sheet I.

l E i awzwzsam' farle No. 705,624. Patented July 29, I902.

C. F. STOKES & G. E. McGLINCHEY.

MOTION TRANSMITTING DEVICE.

(Application filed Nov. 9, 1899.)

2 Sheets-Sheet 2.

(Model.)

CkarZeaZi UNITED STATES;

PATENT ()FEicE.

cHAELEs E. STOKES, or CHICAGO, ILLINOIS, AND CHARLES EDWARD MOGLINCHEY, OF HIGHLANDVILLE, MASSACHUSETTS; SAID MGGLIN- OHEY ASSIGNOR TO SAID STOKES.

MOTION-TRANSMITTING DEVICE.

SPECIFICATION forming part of Letters Patent No. 705,624, dated July 29, 1902.

Application filed November 9, 1899. Serial no. 736.400. ma n.)

To aIZL whom it may concern:

Be it known that we, CHARLES; E. STOKES, residing at Chicago, in the county of Cook and State of Illinois, and CHARLES EDWARD MoGLINcHEY, residing at Highlandville, in

the county of Norfolk and State of Massachusetts, citizens of the United States, have invented a new and useful Improvement in M0- tion-Transmitting Devices, of which the following is a specification.

Our invention relates to that class of gear which is adapted to transmit motion from a driving-shaft to a driven shaft, which shafts are at an angle to each other.

In so-called angle-gearing as heretofore employed three characteristic constructions are found. The first, most common, employs intermeshing bevel-gears. The second, contrived to overcome obvious objections to the bevel-gear, is of the kind termed pin-roller gears, in which in place of bevel-teeth intermeshing rollers are employed which engage each other at an angle. The third is found only in bicycles, so far as we are aware, and employs rollers on the driven-gear member, and upon the drivinggear it employs teeth of peculiar construction intended to engage the driven-gear rollers or pins with line contact and with a minimum of friction.

We have found that all three forms of angle-gearing here described have radical defects, and the defects are in all instances, in our opinion, dueto errors in principle of construction.

It is obvious that to prevent undue and irregular wear of the'intermeshing members one upon the other the largest possible surface of contact between the meshing teeth or substitute for teeth shall be afiorded and that the extent of contact shall, as far as possible, remain unvarying during the time that the driving contact is occurring. It is also 010- vious that as both the gear members are moving upon independent axes, so that the teethv in their movements are as to each set describing arcs at an angleto each other, there is a strong tendencytofrictional wear by the Slide ing of the teeth one upon the other, this sliding being simultaneously in two directions namely, radially of a each gear. This sliding of the teeth upon each other produces friction, which when the gears are intended to be driven at high speed or under high pressure or against a high'resistance produces rapid wearing out of the faces. This wearing not only weakens the gear members and renders them more easily broken, but disarranges the adjustment of the gears, making their action irregular. It is further to be observed that where the engagement of the teeth is such that the application of power is, as it must be, tangential to the gear-body, with a resistance in the same tangential line in the othergear-body, the strength of the gears is the strength of the teeth in cross-section, and

any slight defect'in the metal constituting any tooth renders the gear of doubtful strength.

Some or all of the above objections are found in the three classes of gear herein enunrerated. Thus in the straight bevel-gearing there is an inverse variation in line of contact between the teeth, producing a variation in leverage, a pronounced friction, and a strength equal only to the strength in crosssection of the gear-teeth. In the so-called pin-roller gear the friction is largely overcome; but the contact between the teeth is necessarily a point contact and the Wear is rapid. To the third class of gear above mentioned the criticism is ofiered, among others, that the pressure of the drive-gear teeth in transmitting motion to the driven gear is in the line transverse of the teeth, so that the weight of-metal in the teeth alone is to be looked to for the strength of the member. A flaw or defect in the metal of any tooth renders the gear worthless.

Our invention is contrived with a view to producing angle-gearing which shall be sub* stantially free from all of the defects hereinabove noted, and by the construction herein after described embodying the principle presently noted we produce an angle gearing which is substantially frictionless, which employs the most advantageous leverage in driving one gear by the other, and which permits the strain of the pressure of the teeth one against the other to be in such a direction that the strain on the drive-gear teeth is sustained by the body of the gear and not merely by the projecting tooth. The member having fixed teeth, preferably integral with the gearbody, is termed the drive-gear, and the member having rou nd-faced teeth, preferably pin-rollers, is termed the driven gear; but it is to be understood that the reversal of parts is contemplated as an equivalent construction and an obvious feature of the invention.

To the accomplishment of the objects above set forth our invention consists in anglegearing in which the driven gear has roundfaced teeth arranged to project at an angle from the center of rotation of the gear and preferably, though not essentially, arranged to project radially from the gear center,while the drive-gear has bevel-shaped teeth presenting interdental spaces, a substantial part of the sides of which conform to the surface of the driven-gear teeth throughout the contact.

Our invention consists, further, in anglegearing involving the general features of construction just described, in which the drivengear teeth are in the form of rollers mounted upon pins extending at an angle and prefer ably radially from the gear center.

Our invention further consists in the construction just described, in which the rollers which constitute the driven-gear teeth are frnsto-conical in shape.

Our invention consists, further, in details of construction and combinations of parts, all as hereinafter more fully set forth.

In the drawings we have illustrated the gear embodying our invention adapted more particularly for use in a chainless bicycle, in which it is to be remarked that the shafts are not at a perfect right angle, but usually about six degrees (more or less) off the right angle. It will be understood, however, that the principles of the invention are unchanged whatever the angle of the shafts to each other may be.

In the drawings, Figure l is a view in perspective,showing intermeshing gear members embodying our improvement. Fig. 2 is a view in front elevation of the driven gear. Fig. 3 is a similar view of the driving-gear. Fig. 4 is an enlarged elevation of one of the rollers employed on the driven gear. Fig. 5 is a view in side elevation of the drive-gear. Fig. 6 is a view in side elevation of a tooth of the drive-gear enlarged. Fig. 7 is a plan view of a tooth of the drive-gear, showing part of the adjacent interdental spaces. 8 is a vertical sectional view through a section of the driven gear, showing one form of mounting the rollers; and Fig. 9, a similar view showing another form of mounting the rollers.

A represents the drive-shaft, and B the driven shaft; but it will be understood that this designation is arbitrary, and it may here Fig.

be said that what is termed the drive-gear may be used as the driven gear, and vice versa. The gear-wheel C, termed for convenience the drive-wheel and mounted on the drive-shaft A, is formed from a conefrustum, and in its construction it is preferred to observe the following characteristics: The thickness of the cone-frustum is ap proximately the length of the roller 25, which constitutes the tooth of the driven gear. This thickness affords a root-line of the drive-gear tooth, (indicated on the line w m, Fig. 5.) The vertical line of the tooth from the rootline to the extremity should be approximately the same as the diameter of the roller t at its base. The outer surface of the cone-frustum has the general conical angle indicated by the line y y, Fig. 5; but in practice it is found desirable slightly to curve this line, as

indicated in the figures and in an enlarged view in Fig. 6. The baseline of the interdental space out transversely of the gearblank is approximately parallel with the line of the shaft A, proper allowance being made for clearance. The sides of the interdental space are nearly but not quite straight in practice; but in the case of a very large geartooth the sides of the interdental space may present pronounced variation in its inclination.

It is part of the'invention herein claimed that the sides of the interdental space shall be given such a face contour as to present a transverse line of contact covering a substantial part of the width of the tooth during the whole of the time that the driven-gear tooth is being engaged and driven by the drive-gear tooth.

In the structure herein more specifically shown the interdental space is cut, and the sides thereof are so shaped as'to present the following Variations: The tip of the tooth is rounded, as indicated at 5, Figs. 1, 3, 6, and 7. Below the tip the face is cut away at a gradually-reduced angle of inclination from the line indicated at 1', Figs. 6 and 7, toward the back of the tooth and downwardthat is to say, the angle ofinclination from the line 1' to the back of the tooth is greatest at the point nearest to the extremitys and least at the point nearest the root-line, and near the rootline it may be inclined rearward at an opposite angle to that presented toward the extremity. Moreover, the cutting or inclination is so effected that in the line of the direction presented by the driven-gear tooth when engaging the drive-gear line contact between the members is preserved in the manner presently explained. In the front of the tooth a corresponding variation in the inclination of the interdental space is presented, whereby the inclination is greatest from the line 7 to the front of the tooth at the point nearest the extremity and least at the point nearest the root-line. As a consequence of this construction it will be Obvious thatthe width of points 0, Fig. 6, on adjacent teeth, gradually narrowing forward and downward.

The driven gear comprises the wheel having the central body R, projecting radially from which are the pins L, carrying frusto-conical rollers 25, the opposite ends of the pins L having their bearings in the outer flange or ring R. As a convenient means for securing the pins in place we employ the slip-ring R which slips over the outer face of the ring B after the pins L have been placed in position. The slip-ring may be secured in place by a screw 19. An alternative method of securing the rollers 15 is shown in Fig. 9, in which the upper and lower bearing of the roller is afforded in set-screws 19', passing through the central body R and outer ring R, respectively. The advantage of the modified construction lies in the reduction of friction in the rotation of the roller; but it is not necessarily preferred where strength in the roller is important.

It should here be stated that the shape of the rollers i may depend upon the relative inclination of the drive-gear shaft and the driven-gear shaft. In the form illustrated in the figures, which it may be said represents one mode of employing the gearsfor instance, in chainless bicycles-the drivegear shaft is at an angle of about eighty-five degrees from the driven-gear shaft. For this reason the frusto-conical roller has a surface inclination of five degrees from the cylinder and is made larger at the base than at the extremity. Where the drive-gear shaft is at a right angle to the driven-gear shaft, it is contemplated that the rollers shall be cylindrical and not frusto-conical, and where the drive-gear shaft presents an obtuse angle to the driven-gear shaft then the rollers may be made frusto-conical with the wider end outward. The application of both forms may be illustrated in the use of the gears in chainless bicycles, Where when the drive-gear on the crank is located in the longitudinal center of the bicycle the shaft transmitting motion to the rear-wheel gear presents an obtuse angle to the crank-shaft and involves the employment of frusto-conical rollers having the wider diameter at the outside, .whereas where the drive-gear at the crank is located at the side of the bicycle-frame the line-shaft presents an acute angle to the crank and an ob-' tuse angle to the rear-wheel shaft, necessitating the employment of frusto-conical rollers made larger toward the center of the gear. We desire it expressly understood, however, that the invention is in no sense limited to the use in chainless bicycles, this mention of theconditions which justify a variation in the form of the roller being for clearness of understanding only.

While the teethtare described as rollers, we desire it expressly understood that it is not essential to the operation of the inventiori in'all its novel features that they shall,

in fact, be rollers, it being merely essential that they shall present a rounded face for contact with the drive-gear teeth. To this end the round-faced teeth may be non-rotatory, and may obviously be otherwise than cylindrical, provided that the characteristic is retained that they present a rounded face for varying the line of contact with the drivegear teeth in the manner presently described.

The operation of the gear is as follows, the parts being adjusted substantially as indicated in Fig. 1 of the drawings: Each drivegear tooth begins contact with its intermeshing driven-gear tooth at the rounded point 8 of the former and at or near the outer extremity of the latter. At this time the tendency of the pressure of the drive-gear tooth against the driven-gear tooth is in a direction which if this pressure were relied upon would tend to lift the drive-gear tooth instead of to advance it. In other words, the contact being substantially at the point 0, Fig. 4, and the drive-tooth extremity having a tendency to rise through its arc of rotation there is no driving pressure exerted on the driven teeth, although firm contact is produced. It will be remembered that the next tooth t in advance of the tooth being engaged is receiving full driving pressure from the next drive-gear tooth in advance and that therefore the motion of the drive and driven gear causes the drive-teeth and drivengear' teeth in engagement at s 0, as just described, to advance in the lines of two arcs which first cross each other where the teeth first engage. As the teeth move into mesh the point of engagement between the drive and driven gear rises and advances inwardly on the driven-gear tooth substantially on the spiral dotted line at, Fig. 4, and advances and moves inward along the rearwardly-inclined interdental face of the drive-tooth.

It will further be observed that the angle of variation of the surfaces of contact of the drive and driven gear tooth, respectively, is greatest at the first moment of contact and at the beginning of driving contact is such that to obtain lineengagement the deepestinclination on the interdental face is required, as indicated at 0, Fig. 6. dotted lines, Fig. 5.) As the gears move into mesh the variation in the angle of the engaging surfaces become less and less, while at the same time the extremity of the driven tooth t moves farther and farther into the interdental space of the drive-gear. Hence the interdental surface,'gradually lengthened, permits a slightly-larger surface of drivengear tooth to receive engagement from the drive-gear tooth. The change is gradual, and at the moment of the most intimatemeshing the interdental surface practically engages the whole of the driven-gear tooth. As the engagement of the intermeshing teeth occurs first at a place near the outer extremity of each and changes according to a fixed ratio until at the deepest mesh the contact is at (See places near the bases of both meshing teeth, there is produced a uniform leverage, which contributes materially to the value of the device. The most rapidly moving point of the driving-tooth is in contact with the most rapidly moving point of the driven tooth, and as the line of contact changes on the driving-tooth to the slower moving point it changes also to the slower-moving point of the driven tooth. As the teeth move out of mesh the separation involves a change in the also be produced byshortenin g the drive-gear tooth, whereby it is of a shorter face diameter,

with consequent delay in the engagement of the gear members.

The line of engagement of the drive-gear teeth and driven-gear teeth changes from a point at or near the extremity of the drivengear tooth to a point nearer the base of the tooth, the movement being on a spiral line by reason of rising and advancing on the curved surface. Throughout the period of engagement, however, the line-contact is so near the dead-center line of the driven-gear roller that the whole pressure of driving contact is exerted against the pin which supports the roller, with the consequence that the driving pressure is exerted in advancing the gear to the same extent as if the pin and roller were integral, thus forming a solid tooth.- At the same time, particularly where the driven gear is in the form of a roller, the change of linecontact along the spiral line 0?, produces a rotation of the roller upon its own axis, whereby friction is largely overcome, the friction of the roller on its own axis being immaterial. This rotation of the roller is produced fully as much by the spiral inward as by the spiral upward movement of the teeth one upon the other. It is entirely within our invention, however, entirely to ignore any tendency to friction which may result from the engagement of the teeth, and we therefore desire it understood that the prevention of friction in this manner, though desirable, is not an essential part of our invention.

In the drawings the driven-gear teeth are shown as radial, and it is deemed essential to the successful operation of the gear that a substantially radial relation of the teeth shall be provided; but it will be understood that a variation from a perfect radius is intended to be included under ourinvention,provided that the variation be not so great as to approximate parallelism with the shaft. 7

An important feature of our invention is found in the arrangement which permits the driven-gear teeth to be supported at both ends, and such supportis preferred, although obviously it is not essential to the invention.

What we claim as new, and desire to secure by Letters Patent, is

1. In angle-gearing, the combination of the drive-gear having curved interdental spaces and teeth of greater length at the base than at the extremity, and a driven gear having rounded teeth extending at an angle from the centerof rotation, substantially as described.

2. In angle-gearing, the combination of a drive-gear having the drive-teeth and curved interdental spaces, and having the sides of the interdental spaces formed to maintain line-contact with the driven-gear teeth, and a driven gear having teeth extending at an angle from the center of rotation and adapted to be engaged by the drive-teeth at the extremity of both, such engagement being in line-contact and gradually moving radially of both teeth, substantially as described, whereby the operation of the gears is effected with the most advantageous leverage, as set forth.

3. In angle-gearing, the combination with the driven gear having round-faced teeth extending at an angle from the center of rotation, of a driving-gear frusto-conical in form with curved interdental spaces, the bases of which are substantially parallel with the drive-shaft, the parts being arranged substantially as described, whereby the driveteeth engage the driven teeth ina line changing gradually in a spiralcentripetal direction, substantially as set forth.

4. In angle-gearing, the combination with a driven gear having rotatory teeth extending at an angle from the center of rotation, of a frusto-conical drive-gear having outward-extending conical teeth and curved interdental spaces, the bases of which present a line substantially parallel with the drive-shaft, the parts being arranged to operate substantially as described, whereby the pressure-contact between the teeth is on a spirally-varying line leading toward the center of the driven gear and sliding friction is reduced, substantially as set forth.

5. In angle-gearing, the combination with the driven gear having round-faced teeth, of a drive-gear frusto-conical in shape and having bevel-teeth and curved interdental spaces, said interdental spaces being. warped at their rear extremities to afiord freedom of movement of the extremity of the driven -gear tooth in its movement through its arc, substantially as described.

6. In angle-gearing, the combination with the driven gear having the round-faced radially-extending teeth, of a drive-gear frustoconical in shape and presenting interdental spaces of greater expanse at the rear than at 1o terdental space is greater at the face of the the forward end and having the edges of the teeth at the front rounded to permit ready withdrawal of the teeth extremities from between the driven teeth in the movement of the gear, substantially as described.

7. In angle-gearing, the combination of a frusto-conical drive-gear having peripheral interdental spaces out transversely of the gear-body on a line substantially parallel with the drive-shaft, whereby the depth of the ingear than at the back, and a driven gear having radially-projecting rotatoryteeth supported substantially as described.

8. In angle-gearing, the combination of a frusto-conical drive-gear having peripheral interdental spaces cut transversely of the gear-body on a line substantially parallel with the drive-shaft, whereby the depth of the interdental surface is greater at the face of the gear than at the back, and a driven gear having radially-projecting rotatory f rusto-conical teeth supported substantially as described.

9. In angle-gearing, the combination with the driven gear having radially-projecting frusto-conical teeth supported at both ends, of a drive-gear frusto-conical in form with curved interdental peripheral spaces cut transversely of the gear-body on a line substantially parallel with the drive-sl1aft,whereby the interdental space is deeper at the outer than at the inner end thereof relative tothe teeth, the said teeth being of a length to engage the surface of the driven teeth without shock between the gear members, and in the driving operation the driving-teeth move in a line spirally upon the driven teeth and toward the center of the driven gear, and friction is reduced by the rotation of the drivengear teeth on their axes, all as set forth.

10. In an gle-gearing, the combination with a driven gear having round-faced teeth projecting at an angle from the center of rotation, of a drive-gear having radially-projecting teeth and interdental spaces, the sides of which are formed to conform to theopposing face of the driven-gear teeth during driving are formed to maintain line-contact with the driven-gear teeth throughout the period of the application of driving power, substantially as described.

CHARLES F. STOKES. CHARLES EDWARD MOGLINCHEY.

Witnesses to the signature of Charles F. Stokes:

J. W. DYRENFORTH, D. W. LEE.

Witnesses to the signature of Charles E. McGlinchey:

F. I. WETHERBEE, FRANK GARVEY. 

